Research On Silicon Integrated Magneto-optical Nonreciprocal Devices

After entering the era of big data,the huge amount of data from information interaction generated higher requirements on the bandwidth and speed of communication systems.Silicon photonics has become one of the core technologies supporting the new generation of optical communication and optical interconnection due to its unique advantages of small device size,low energy consumption,and CMOS process compatibility.After more and more optical components are integrated on the silicon platform,integrated optical chips gradually applied.But nonreciprocal optical devices such as optical isolators and optical circulators are still discrete devices,which severely restricts the cost and application of silicon photonics technology.Therefore,the research of integrated nonreciprocal optical devices has great value.This research focus silicon integrated nonreciprocal optical devices based on the magneto-optical nonreciprocal phase shift effect,and use monolithic integration technology to integrate the magneto-optical material on the silicon platform.The principle of magneto-optical effect and optics used in integrated devices are explained;and the principle of nonreciprocal transmission in integrated magneto-optical devices is discussed.The device design and preparation work is mainly divided into the following two parts:(1)MZI type magneto-optical isolator.The new device design reduces the device size to 400 ?m×210 ?m,and enables the device to work under a unidirectional magnetic field,simplifying magnetic field integration.By optimizing the polarization rotator structure,3 dB coupler structure and magneto-optical material deposition window structure,the insertion loss of the device is reduced.Finally we design and fabricate the low-loss monolithic integrated TE and TM mode broadband magneto-optical isolator.Insertion loss of TM mode device is 4.5 dB,isolation ratio is 30 dB;Insertion loss of TE mode device is 9 dB,isolation ratio is 30 dB.(2)MMI type magneto-optic circulator.Based on the slot waveguide,a unique magneto-optical waveguide structure is constructed,and a magneto-optical circulator which works directly in TE polarized is realized.The theoretical insertion loss of the device is 1.75 dB,and the crosstalk is less than 50 dB.By designing an ultra-wideband 3 dB coupler and adjusting the inter-mode dispersion in the magneto-optical waveguide,a broadband TE mode magneto-optic circulator is constructed.The insertion loss of the device in the 14 nm wavelength range is less than 3 dB,and the crosstalk is less than 20 dB.